Lightweight automotive headlight reflectors and bezels can be prepared by metallization, in which a thin light-reflecting metal layer is coated onto a thermoplastic substrate molded from a plastic such as polyester. A primer coat can be applied to the plastic substrate to provide a high surface gloss, and also to minimize distortion or “hazing” of the reflective metal layer when, in operation, the reflector or bezel encounters high temperatures and the outgassing of the thermoplastic substrate occurs. Outgassing is evaporation of volatile organic compounds from the plastic and concomitant condensation of the volatile organic compounds on nearby cooler surfaces, which causes the hazing.
Thermoplastic substrates exhibiting reduced outgassing at headlight operating temperatures are desirable. Ideally, the outgassing should be reduced enough for the primer coat to be omitted, so that the thin light-reflecting metal layer can be coated directly onto the plastic substrate. Outgassing of polyesters may be reduced to some extent by addition of a catalyst quencher, which reduces the activity of the catalyst in the melt. However the reduction in outgassing is limited, and may not be sufficient to provide articles having high surface gloss and free of visible surface defects, and to allow removal of the primer coat for metallized articles. There remains a need for an effective method to reduce outgassing of polyesters so that primer coat of metallized substrates can be omitted.